Devices for rendering video data are well known, for example video players like DVD players, BD players or set top boxes for rendering digital video signals. The rendering device is commonly used as a source device to be coupled to a display device like a TV set. Image data is transferred from the source device via a suitable interface like HDMI.
With respect to the coded video information stream, for example this may under the format known as stereoscopic, where left and right (L+R) images are encoded. Alternatively, a coded video information stream may comprise a 2D picture and an additional picture (L+D), a so-called depth map, as described in Oliver Sheer—“3D Video Communication”, Wiley, 2005, pages 29-34. The depth map conveys information about the depth of objects in the 2D image. The grey scale values in the depth map indicate the depth of the associated pixel in the 2D image. A stereo display can calculate the additional view required for stereo by using the depth value from the depth map and by calculating the required pixel transformation. The 2D video+depth map may be extended by adding occlusion and transparency information (DOT).
Currently in 3D systems, a known solution for the output video data to be transferred via the HDMI interface to the 3D display is time interleaving, wherein frames corresponding to Left or 2D information are interleaved with Right or DOT frames.
It is known that, for 2D video systems, application formats such as for distribution of video content and playback devicem support overlay or real time generated graphics on top of the video. Overlay graphics arem for example, internally generated by the player device for on screen display (OSD) menus, or received, such as subtitles or other graphics.
However extending the known overlay models to 3D systems creates the problem that the performance requirements of drawing routines for the real-time generated overlay graphics are increased.